Precast fireplace, methods of manufacture and erection



1 t v m. S CW a 3 e h SI Jan. 31, 1967 s. J. HENDRICKS PRECAST FIREPLACE, METHODS OF MANUFACTURE AND ERECTION Filed June 5, 1964 5/0A/EV d. HENDE/C/(S 5} HIS ATTORNEYS HAee/s, K/scw, RUSSELL &/(RA/ Jan. 31, 1967 s. J. HENDRICKS 3,301,249

PREGAST FIREPLACE, METHODS OF MANUFACTURE AND ERECTION Filed June 5, 1964 5 Sheets-Sheet 2 Fins was FIG-10. 95

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United States Patent Ofiice 3,301,249 PRECAST FIREPLACE, METHODS OF MANU- FACTURE AND ERECTION Sidney J. Hendricks, Buena Park, Calif., assignor to Prekast Fireplace Manufacturing Company, La Mirada,

Calitl, a corporation of California Filed June 3, 1964, Ser. No. 372,227 6 Claims. (Cl. 126-129) This invention relates to chimney structures and more particularly to a precast chimney structure and to its method of manufacture and method of erection at the construction site.

Historically, the chimney structure including fireplace and stack has been built of bricks or native stone held together by mortar with each brick or stone being individually handled and placed into position by a mason. It has been estimated that a typical fireplace for a modern home incorporates over 1,200 pieces of some 20 different types of materials, all of which must be delivered to the job site. Three man days or more are normally required for the erection of the chimney structure, which not infrequently will fail to meet the building code specifications because of inferior workmanship or materials.

Too often the subcontractor or mason leaves the job site untidy and labor and time must be spent in clearing the area. It will be appreciated that manually erected chimney structures are not uniform in quality and because of the large amount of labor involved, it is difficult to estimate precisely the cost of building a particular chimney structure at a job site where there is to be an assembly of such a large number of pieces.

It is a principal object of the invention to provide a precast or preformedchimney structure including a fireplace and stack of uniform and superior quality.

It is another object of the invention to provide a precast chimney structure of a novel design or construction which facilitates its erection at .the job site.

It is another object of the invention to provide a precast chimney structure including a separately cast firebox having a concrete encasement thereabout completing the fireplace and stack.

It is a further object of the invention to provide a method of erecting a chimney structure which minimizes untidiness at the job site.

It is a further object of the invention to provide a method of erecting a chimney structure which because ter of a few minutes, thus avoiding delays common in building schedules.

It is a still further object of the invention to provide a precast chimney structure and method of erection which permits the installers to move through a tract of homes with assembly-line precision and in a day or a few days position all of the chimney structures of the houses of the tract.

It is a still further object of the invention to provide a method of manufacturing chimney structures, preferably at a single site, using equipment which will assure uniform construction not found in conventional fireplaces.

The precast chimney structure of the invention which includes fireplace and stack is preferably made up of a separately cast firebox having an overhead stack opening and a hearth opening. A concrete encasement placed about the firebox substantially encloses the vertical sides of the firebox excepting the hearth opening, forming a fireplace which is integral with a concrete stack having a The firebox may be manufactured with a plurality of hearth openings, as, for example, two opposed openings as present in look-through fireplaces located between adjoining rooms. The firebox may also be manufactured for a Swedish angle fireplace of the type having adjoining vertical hearth openings in which instance a corner support rod at the adjoining corners of the two openings the structure.

is desirably used. The firebox is made of refractory material, preferably a refractory concrete, with its bottom serving as the hearth of the fireplace.

In the preferred embodiment of the chimney structure I, of the invention, the concrete encasement substantially encloses, the firebox except for its openings and providesa hearth support slab adjoining the underside of the firebox. The bottom surface of the hearth supporting slab desirably slopes upwardly away from the hearth side of Preferably, the hearth support slab is set back from the hearth face of the firebox to provide an overhanging ledge formed of the precast firebox. The

foregoing configuration of the hearth support slab as here inafter described facilitates the erection of the precast chimney structure and makes the erected structure more stable to earthquakes.

In some instances, for example, where the precast chimney structure is being placed against an inside wall, it may be more desirable to use a structure having no hearth supporting slab and here the hearth bottom of the firebox will rest directly on a reinforced base.

In the erection of the chimney structure of the invention, the preformed structure is erected at the building site in an upright position with the overlying ledge at the hearth side at the bottom of the structure resting on a shoring which will ordinarily be the foundation of the house. The erected chimney is preferably slightly tilted towards its hearth side. A concrete footing is poured beneath the tilted chimney structure adjacent the shoring. Thereafter and while the concrete is still sufficiently plastic, the tilted chimney structure is brought into plumb, thus permitting the bottom surface of the lower end of the structure to rest upon the concrete footing and in the instance where the hearth support slab is inclined to impart an inclined surface to the footing. The inclined surface of the footing will slope downwardly towards the shoring. With this arrangement of complementary slopingsurfaces of the concrete footing and the bottom surface of the chimney structure, the chimney structure is urged continually towards the house.

The foregoing and other objects of the invention will become more apparent in the following specification and drawings wherein:

FIG. 1 is an isometric view from above, of the inside face of the preferred embodiment of the chimney structure of the invention showing veneer tabs, anchor rods, and some firebox details;

FIG. 2 is an isometric view, from below, of the backside of the chimney structure of FIG. 1, illustrating the 10- cation of the ash clean-out pit and longitudinally extending reinforcing rods;

FIG. 3 is a longitudinal sectional view of the chimney structure of FIGS. 1 and 2;

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3 showing details of the stack of the chimney structure;

FIG. 5 is a cross-sectional view taken alongline 55 of FIG. 3 illustrating details of the bottom portion of the chimney structure;

FIGS. 6 and 7 illustrate various finishes which may be imprinted on'the stack of the chimney structure of the invention;

FIG. 8 is a diagrammatic representation of an assembly line showing the manufacture of the precast chimney structure of the invention;

FIG. 9 is a side elevation of a mold mounted on wheels and ready for the pouring of concrete;

FIG. 10 is a cross-sectional view of the mold of FIG. 9 taken along line .10-10 of that figure illustrating in par- Patented Jan. 31, 1967 I J ticular how the firebox is supported within the mold before the pouring of the concrete;

FIG. 11 is a cross-sectional view taken along line 11 11 of FIG. 9 illustrating the stack portion of the mold and showing in particular the toggle and pivot arrangement ofthe vertical sides of the mold;

v FIG. 12 is a longitudinal sectional view through a mold for the casting of the firebox later incorporated in the chimney structure of the invention;

FIG. 13 is a longitudinal sectional view, partly in elevation, illustrating an alternative flue form employing an inflatable tube; I t I FIG. 14 is an elevational view-of the mold for the precast chimney structure generally resembling that of FIG. 9, but with the mold turned upside down with respect to the position of FIG. 9;

FIG. 15 is a side elevational view illustrating the erection of the chimney structure of the invention upon anedge of a concrete foundation;

FIG. 16 is a side elevational view illustrating'the chimney structure tilted slightly in the direction of itshearth face; i

FIG. 17 is a side elevational view of the chimney structure in its erected plumb position; and

FIG. 18 is a plan view of an erected chimney structure of the invention with laterally extending anchor rods 8 fixed to ceiling joists of the house framing. 1

Asbest seen in FIGS. l-3, a chimney structure 10 of the presently preferred form of the invention comprises a fireplace 12 and a stack 14. In more detail, thestructure includes a separately cast firebox16 made of refractory material having anoverhead stack opening 18, vertical side walls 20 and 22, aside or rear wall 24, vertical hearth opening 2-6, and a, bottom or hearth. 28. A short sloping top wall 30 extends rearwardly from the top of the vertical hearth opening to the stack opening'lS of the: firebox. The firebox 16is provided with a threat 32 defined by the sloping top or forward wall30 and a protrusion 34 of the vertical backwall 22,. A concrete encasement 36 substantially encloses the sides of the firebox 16, excepting the hearth and stack openings, and provides a hearth support slab 38 adjacent the underside of the firebox, In the preferred embodiment illustrated in FIGS. 1-3, the hearth support slab 38 is set back from the hearth face of the firebox to provide an overhanging ledge 42. As best seen in FIGS. 3 and 15, the bottom surface of the concrete encasement, that is, the hearth support slab 38, slopes upwardly away from the hearth side of the chimney structure. I

The concrete encasement 36, together with the firebox 16, comprises the fireplace 12.. The stack 14, also made of concrete, :is integral with the concrete encasement 3'6 with a flue 37 of the stack opening into the stack opening 18 of the firebox 16. The concrete of the structure is desirably reinforced with a network 50 of steel rods comprising longitudinally extend-ing rods 52 equally spaced inwardly from the four corners of the stack and extended to reinforce the concrete encasement about the firebox, as seen in FIG. 5. It is desirable that the hearth support slab 38 also be reinforced with steel rods. The longitudinally extending rods 52 which commence adjacent the top of the stack 14 extend to a point beyond the lower end of the chimney structure to provide vertical anchor rods 54 for embedment in a concrete footing upon installation. The reinforcing network is provided with spaced lateral tie rods 56 which are wrapped about the vertical rods 52. i

The hearth 28 of the firebox 16 adjacent its rear side is provided with a cutaway hole 29 which overlies an elongated ash removal pit 31 formed in the hearth support slab 38 with the ash removal pit opening to the rear side of the structure.

The precast firebox 16 is manufactured in the form or mold illustrated in the sectional view of FIG. 12. The sloping top wall 30 of the'firebox is formed in a cavity 60 and the back vertical wall 22 and its protrusion 34 are formed in an area 62 of the mold. The hearth 28 is cast in a cavity 64. It will be seen that the firebox form is built to permit disassembly and the removal of a core portion 66 of the form through an access 68. The view of FIG. 12 being a longitudinal section, the cavity areas for formation of the vertical walls 20 and 24 of the firebox 16 are not shown.

The firebox 16 is formed of. refractory material, preferably employing an aluminous or high-alumina cement (Lumnite), using two parts of the cement to four parts of sand and four to five parts of gravel. The aggregate is preferably an expanded lightweight clay (Ridgelite). It has been found that the firebox is satisfactorily formed with a two-inch thickness. It will be appreciated that asuitable refractory firebox may be used employing other materials. High-alumina cement is used both for its fire resistance and refractory properties. Under increasing temperature, high-alumina cement will lose less water and less strength than does common Portland cement which becomes substantially dehydrated at relatively low temperatures. Refractory materials using alumina cement appear to acquire a fuse bond which replaces the strength fully employed.

A suitable form 67 for the casting of the over-all chimney structure is illustrated in FIGS. 9, 10, and 11. The form 67 has the general configuration of the desired chimney structure and includes, in the embodiment illustrated, an enlarged fireplace portion 70 opening into a narrow, elongated, stack portion 72. The vertical longitudinal walls of the two portions 70 and 72 of the chimney structure form are hinged to permit simultaneous outward movement, thus facilitating the removal of the completed chimney structure therefrom. Referring to FIG. 11, it will be seen that the vertical walls 76 are hinged to the bottom of the form 67 and deta-chably locked in an upright position by a toggle locking arrangement 78. Two such toggle arrangements 78 are disposed along the length of the stack portion 72 of the mold form. A similar toggle arrangement may be provided on the fireplace portion 70. Upright, longitudinal walls 84 of the fireplace portion 70, each having a horizontally disposed flange section 86, are hinged to the bottom of the mold form 67.

In the particular embodiments of the chimney structure and mold illustrate-d, the stack 14 is narrower than the fireplace 12; however, this need not be as the structure may be manufactured with the stack and fireplace having the same or nearly the same outside dimensions.

The steps involved in the manufacturing of the chimney structure of the invention are best understood with reference to FIG. 8. In the far right top portion of the figure, a firebox mold form 88 is illustrated. In the succeeding step of the process refractory concrete is supplied through a chute 90 to the firebox form 88 and the firebox form is thereafter transferred to a curing tunnel or room 92 and here the firebox may be cured at an elevated temperature of say F. In the next step, the firebox form 88 is removed from the tunnel 92 and the firebox 94 removed from the mold form. As the first step in the assembly of the over-all chimney structure form 67 for the subsequent pouring of theconcrete to form the encasement about the firebox and the integral stack, the reinforcing steel network 50 described previously is positioned within the chimney structure form 67. Referring to FIG. 11, it will be seen that the reinforcing network 50 within the stack portion 72 of the mold form is supported therewithin by suspension rods 102 which are held to lateral crosspieces 104 which rest on flanged upper ends 106 of the pivoted vertical walls 76. In the particular cross section illustrated in FIG. 11, the suspension rods 102 are permanent-.

ly left in place and have laterally extending anchor portions 108 that secure the stack 14 of the erected chimney structure to the house. However, at different locations (and in some instances) along the length of the stack portion 72 of the mold, some of the suspension rods 102 may be removably held to the crosspieces 104.

As the next step in assembly of the mold, the firebox 94 is positioned within the fireplace section 70 of the mold (FIG. with the firebox being held therein by several removable suspension rods 96 which at their upper ends are supported from crosspieces 98. An elongated flue form 110 is positioned within the stack, being held at its inner end within the stack opening 18 of the firebox 16 and at its outer end by an end form 112 which has four sloping walls 113.

With the location of the flue form-110, concrete may now be poured into the mold form via chute 116 following the pouring and troweling of the concrete, if a brick (see FIGS. 6 and 7) or similar finish is desired on the upper portion of the stack 14, plastic form pads 118 are located at the outer end of the stack portion of the mold form as indicated in FIG. 8 and pressed into the concrete. The fireplace portion and stack portion, respectively, of the mold form are lined with plastic form material 120 and 122.

The supporting rods 96 of the firebox 16 of the reinforcing steel network 50 are removed after the poured concrete has been vibrated and has become stiff enough to support the firebox and steel network. Prior to pouring of the concrete into the mold form 67, it is desirable to close off the hearth face of the firebox 16 with a closure plate 124 (FIG. 9). Following the pouring and vibration of the cement. the form 67 may be removed on a wheeled carriage 126 along a track 128 into curing tunnel 130. Following curing and removal of the form 67 from the curing tunnel 130, the respective sides 76 and 84 are moved outwardly as illustrated in the last drawing as the flow diagram of FIG. 8 to permit removal of the completed chimney structure. The flue form 110 is removed from the chimney structure as soon as the latter comes out of the tunnel.

There is illustrated in FIG. 13 an alternative flue form which comprises an inflatable tube 135 which is held in place by a plurality of arcuate rods 139 which are removabiy fixed to the form proper. The inflatable tube flue form 135 may also be weighted by water 131 to reduce the tendency for the tube to move about within the mold 67.

FIG. 14 shows the mold 67 asembled in an inverted form wherein the back vertical wall 22 of the'firebox 16 is up in contrast to the preferred form of FIG. 9 wherein the hearth opening is at the top side.

The manner of erecting the chimney structure at the job site is illustrated in FIGS. -18. In FIGS. 15, 16, and 17 the erection precedes the framing of the house. This is optional and in many instances it.will be found desirable to install the precast chimney structure following framing, there having been left the standard fireplace opening into which the chimney structure is inserted. Referring to FIG. 15, a small crane 133 holding the chimney structure in an upright position rests the ledge 42 on a shoring 132 which in this instance is the foundation of a house. It will be seen that the stack 14 (FIG. 3) centrally of its length and immediately below the laterally extending rods on the hearth side of the structure, is provided with an internally threaded hole 135 which receives the threaded end of an adjustable shoring brace 134. The shoring brace 134 at its other end is fixed to the foundation 132. As the next step (FIG. 16) in the installation of the chimney structure, the structure is tilted usually (but not necessarily) to its hearth side up to about 5 causing the structure to pivot about its ledge 42 and to elevate its sloping bottom surface. It will be noted that the latter surface slopes upwardly from the hearth side. A footing hole 136 somewhat larger in cross section than the bottom of the chimney structure, say about six inches wider all the way around and one foot or so below the end of the chimney structure, is provided and into this a steel mat is located and concrete poured. While the concrete is still :plastic, the chimney structure is brought into plumb (FIG. 17) by turning a handle 137 of the adjustable shoring brace. FIG. 18 shows the erected and plumb fireplace held by its anchor rods 108 to the ceiling joists 138 of a house fra me.

With reference to FIGS. 1 and 2, it will be seen that the concrete encasement on the hearth side about the firebox is provided with the veneer tabs 144 which are used for anchoring the desired facing whether it be new brick, stone, slump stone or other facing material includinga precast facing.

Various arrangements may be employed for installation of the damper and, this not being a part of the invention, has not been illustrated.

Although exemplary embodiments of the invention have been disclosed herein for purposes of illustration, it will be understood that various changes, modifications, and substitutions may be incorporated in such embodiments without departing from the spirit of the invention as defined by the claims which follow.

1. A precast chimney structure including a fireplace structure and stack, said chimney structure comp-rising:

a separately cast thin walled firebox made of refractory material having an overhead stack opening and a vertical hearth opening;

a concrete encasement having relatively thick walls about said thin walled firebox forming a fireplace and substantially enclosing said firebox excepting the openings thereto and integral therewith a concrete stack having a flue opening into the stack opening of the firebox;

and said chimney structure being further characterized by longitudinally extending steel rods embedded in the fireplace end of the structure and reaching below such structure to provide exposed anchor rods for embed-ment in a concrete supporting base upon erection of said precast chimney structure;

the bottom surface of the concrete encasement adjoining the underside of said firebox sloping upwardly away from the hearth side of the structure.

2. A precast chimney structure including fireplace and stack, said structure comprising:

a separately cast thin walled firebox made of refractory mate-rial and having an overhead opening, a vertical hearth opening, and a bottom having a hole for ash removal; and

a concrete encasement having relatively thick walls about said thin walled firebox substantially enclosing the sides and bottom of said firebox excepting the openings therein, with a section of the portion of the concrete encasement adjacent the firebox bottom being cut away beneath the hole of the firebox bottom to provide an ash removal pit, said concrete encasement about the firebox forming a fireplace and integral therewith a concrete stack having a flue in alignment with the stack opening of the firebox, said concrete encasement having embedded therein a network of steel reinforcing rods;

the bottom surface of the concrete encasement adjoining the underside of the firebox sloping upwardly away from the hearth side of the structure.

3. A precast chimney structure comp-rising a fireplace having a hearth opening and an integral stack formed of concrete with a portion of the bottom end of the structure set back to form an overhanging ledge at the hearth side of said structure and with the bottom surface of the lower end of the structure sloping upwardly away from the 7 hearth side of said structure, said chimney structure being further characterized by longitudinally extending steel rods embedded in the fireplace end of the structure and reaching below said structure to provide exposed anchor rods for embedment in a concrete supporting base upon erection of said precast chimney structure.

4. A precast chimney structure comprising a fireplace having a hearth opening and an integral stack formed of concrete with the bottom surface of the lower end of the structure sloping upwardly away from the hearth side of said structure, said chimney structure being further characterized by longitudinally extending steel rods embedded in the fireplace end of the structure and reaching below said structure to provide exposed anchor rods for embedment in a concrete supporting baseupon erection of said precast chimney structure.

5. A precast chimney structure comprising a fireplace having a hearth opening and a stack formed of concrete with a portion of the bottom end of the structure set back to form an overhanging ledge at the hearth side of said structure and with the bottom surface of the lower end of the structure sloping upwardly away from the hearth side of said structure, said chimney structure being further characterized by longitudinally-extending steel rods embedded in the fireplace end of the structure and reaching below said structure to provide exposed anchor rods for embedment in a concrete supporting base upon erection of said precast chimney structure.

6. A precast chimney structure including a fireplace structure and stack, said chimney structure comprising:

a separately cast thin Walled firebox made of refractory material having an overhead stack opening and a vertical hearth opening,

a concrete encasement having relatively thick Walls about said thin walled firebox forming a fireplace and substantially enclosing said firebox excepting the openings thereto :and'integral therewith a concrete stack having a flue opening into the stack opening of the firebox; and

said chimney structure being further characterized by longitudinally extending steel rods embedded in the '8 fireplace end of the structure and reaching below such structure to provide exposed anchor rods for embedment in a concrete supporting base upon erection of said precast chimney structure; a portion of only the bottom end of said encasement being set back at the bottom level of said firebox, from the front of said fireplace whereby said encasement forms an overhanging ledge at the front of said structure.

References Cited by the Examiner UNITED STATES PATENTS D. 175,632 8/1955 Normile 126-120 748,242 12/1903 Weber -124 1,121,319 12/1914 Ambursen 264-275 1,161,914 11/1915 Wayland 126-120 1,281,408 210/1918 Marqueso 264-275 1,326,400 12/1919 Halverson et a1. 264-35 X 1,629,012 5/1927 Trimble 126-120 1,678,504 7/1928 Glover 50-534 1,708,790 4/1929 H all 126-120 X 1,711,090 4/1929 Ford et a1 126-120 1,773,359 8/1930 Hilliard 50-534 1,937,306 11/1933 Barriball 249-16 2,097,214 10/ 1937 Peterson. 2,104,875 1/1938 Levy 50-186 2,497,887 2/1950 Hilpert 50-80 2,595,142 4/1952 Her-ck 264-34 X 2,691,291 10/ 1954 Henderson 52-236 2,707,464 5/1955 Gillen 126-121 2,821,975 2/1958 Thulman 126-120 3,096,754 7/1963 Howrey 126-120 FOREIGN PATENTS 552,897 2/1958 Canada. 1,086,006 8/ 1954 France.

11,956 1907' Great Britain. 532,335 1/1941 Great Britain. 525,930 5/ 1955 Italy.

FREDERICK KETTERER, Primary Examiner. 

1. A PRECAST CHIMNEY STRUCTURE INCLUDING A FIREPLACE STRUCTURE AND STACK, SAID CHIMNEY STRUCTURE COMPRISING: A SEPARATELY CAST THIN WALLED FIREBOX MADE OF REFRACTORY MATERIAL HAVING AN OVERHEAD STACK OPENING AND A VERTICAL HEARTH OPENING; A CONCRETE ENCASEMENT HAVING RELATIVELY THICK WALLS ABOUT SAID THIN WALLED FIREBOX FORMING A FIREPLACE AND SUBSTANTIALLY ENCLOSING SAID FIREBOX EXCEPTING THE OPENINGS THERETO AND INTEGRAL THEREWITH A CONCRETE STACK HAVING A FLUE OPENING INTO THE STACK OPENING OF THE FIREBOX; AND SAID CHIMNEY STRUCTURE BEING FURTHER CHARACTERIZED BY LONGITUDINALLY EXTENDING STEEL RODS EMBEDDED IN THE FIREPLACE END OF THE STRUCTURE AND REACHING BELOW SUCH STRUCTURE TO PROVIDE EXPOSED ANCHOR RODS FOR EMBEDMENT IN A CONCRETE SUPPORTING BASE UPON ERECTION OF SAID PRECAST CHIMNEY STRUCTURE; 